The PopulateCache policy is a general-purpose caching policy used to write the value of any flow variable, which is treated as a string, into the cache. This makes it highly flexible for caching arbitrary data within an API proxy flow.

The ResponseCache policy is a specialized policy designed for performance optimization. It automatically caches the entire HTTP response message from a target, including the status code, headers, and body. When a subsequent identical request is received, Apigee serves the response directly from the cache, avoiding a round trip to the backend.

A. The element in the PopulateCache policy supports TimeoutInSec, TimeOfDay, and ExpiryDate, but not a TimeOfYear option.

C. The ResponseCache policy is a single, unified policy that handles both cache lookups and population. In contrast, general-purpose caching uses separate policies: LookupCache, PopulateCache, and InvalidateCache.

1. Google Cloud Apigee Documentation

"PopulateCache policy":

Regarding option B: The documentation for the element states

"The variable whose value will be written to the cache." This confirms it caches the content of a variable

which is treated as a string.

Regarding option A: The documentation for the element lists only ExpiryDate

TimeOfDay

and TimeoutInSec as valid child elements for controlling cache entry expiration.

2. Google Cloud Apigee Documentation

"ResponseCache policy":

Regarding option D: The overview section explicitly states

"The ResponseCache policy caches the full response from a backend target

including headers

and status code."

Regarding option C: The documentation presents the ResponseCache policy as a single configuration. The section "Element reference" shows a single element that contains all configuration for both lookup and population logic

contrasting with the separate policies used for general-purpose caching.